After some research here are some other differences according to a comparison between the two models:

"The Shokz OpenRun Pro is the improved variant of the Shokz OpenRun Bone Conduction. While both helmets are comfortable, the Pro comes with a better hard case to protect the helmet when not in use. They're also able to reproduce a bit more bass, though it's probably not enough if you like loud genres like EDM and hip-hop. That said, their companion app offers some EQ presets to help you adjust their sound. The OpenRun have a higher IP67 rating for dust and water resistance."